50thKaikoura05 -1- Kaikoura 2005 CHARACTERISATION OF NEW ...

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millennial scale dating of deep-water sediments, using a non-linear age interpolation method, and facies analysis, based on minimum paleodepth data. When applied in combination, the new biostratigraphic tools provide a robust temporal and paleoenvironmental framework that enables the temporal and spatial relationships of late Miocene depositional systems to be interrogated at a level of resolution similar to seismic. Although developed for late Miocene depositional systems in Taranaki Basin, the new biostratigraphic tools can be applied to late Miocene rocks in most New Zealand sedimentary basins, and the methodologies adapted for other stratigraphic intervals. ORAL A PROBABILISTIC LANDSLIDE HAZARD MODEL FOR NEW ZEALAND G.D. Dellow 1 , M.J. McSaveney 1 ,M.W.Stirling 1 & K.R. Berryman 1 1 GNS Science, PO Box 30-368, Lower Hutt, New Zealand. (g.dellow*gns.cri.nz) A probabilistic landslide hazard model for New Zealand has been developed, by producing landslide-area magnitude/frequency curves. Calibrating the magnitude/ frequency curves using landslide catalogue data allows the absolute and relative frequency of landslide-areas of a stipulated magnitude or in a stipulated time interval to be determined for a selected terrain. Landslide-area data for New Zealand have been subdivided into landslide terrains based on geology, slope angle and landslide density. For each landslide terrain the landslide-area data (from an inventory of New Zealand landslides) is plotted as a magnitude/frequency curve in log/log space. The slope of the magnitude/frequency curve in log/log space approximates a straight line for the larger magnitude landslide-area data in each terrain. The slope of the magnitude/frequency curve varies for different terrains indicating that the landslide hazard varies across the different terrains. The slopes of the magnitude/frequency curves for the New Zealand landslide terrains range from 1.25 to 2.94 and are similar to the range of values reported in the literature for landslide magnitude/frequency data (1.75-3.30). The magnitude/frequency curves are calibrated with respect to time using a nine-year catalogue of landslide occurrences in New Zealand. This allows the absolute landslide-area magnitude/frequency curve for each terrain to be determined. To directly compare the landslide magnitude/frequency curves in each of the terrains, we calculate the relative landslide magnitude/frequency curves by normalising terrain areas to a standard area unit of 10,000 km 2 . Comparison of the relative landslide magnitude/frequency curves shows an order of magnitude difference in the rate at which landslides occur in the lowest and highest hazard terrains. The relative landslide magnitude/frequency curves determined for each terrain allow probabilistic landslide hazard maps for New Zealand to be generated. Probabilistic landslide hazard maps for New Zealand are used to show either the largest landslide that is expected to occur in a given terrain for a stipulated time interval (e.g. 100 or 475 years) or alternatively the return period for a stipulated landslide-area (e.g. 10,000 m 3 ; 100,000 m 3 or 1,000,000 m 3 ). ORAL THE VOLCANOLOGY AND GEOCHEMISTRY OF THE 13.8 – 22.5 KA ROTOAIRA ERUPTIVE SEQUENCE, TONGARIRO VOLCANIC CENTRE, NEW ZEALAND Louise R. Doyle 1 , Phil Shane 1 &IanNairn 2 1 Department of Geology, University of Auckland 2 45 Summit Road, Rotorua (l.fowler*auckland.ac.nz) This study focuses on the 13.8 – 22.5 ka Rotoaira eruptive sequence, the youngest of which is the Rotoaira Lapilli (13.8 ka). Three units make up the distal deposits of the Rotoaira eruptive sequence, Tongariro Volcanic Centre, and are bracketed by the rhyolitic 11.9 ka Waiohau and 22.5 ka Oruanui tephras. Rerewhakaaitu tephra (14.7 ka) lies between the youngest and the middle deposit of the Rotoaira sequence. All three units are separated by paleosols. Glass, mineral and whole rock geochemistry has been carried out on lapilli-sized pumices from the distal, medial and proximal deposits of the three units of the Rotoaira eruptive sequence. Each unit has a distinct geochemical composition. Glass data indicate many of the clasts are heterogeneous and each eruptive episode has a wide range in SiO2 (58-78 wt %) and K2O (1.6-4.0 wt %) composition suggesting magma mingling. Disequilibrium features in thin sections are further evidence of magma mingling. Temporal variations in composition are apparent. The oldest deposit of the eruption sequence (PR1) is less evolved than the younger deposits (SiO2=62 wt %), the middle deposit (PR2) has SiO2=66 wt % and the final eruption deposit has bimodal chemistry of SiO2=64 wt % and SiO2=71 wt %. Temporal variations are also evident within the youngest deposit of the eruption sequence (PR3). The oldest stratigraphic layer has SiO2=69 wt %, the middle layer has an increased SiO2 composition (SiO2=72 wt %) with a 50 th Kaikoura05 -24- Kaikoura 2005
wider range. The youngest layer has a bimodal composition with distinct modes at SiO2=64 wt % and SiO2=73 wt%. This may indicate several small pockets of magma were being sequentially tapped during the eruption. Individual clasts from two of the three eruptions contain compositions similar to Taupo Volcanic Zone rhyolites. This could imply that bodies of rhyolitic magma resided farther south than the existing calderas. Fe-Ti oxides demonstrate a wide range of temperatures (787- 1194°C) and oxygen fugacities (NNO-0.98 to +0.98). All three eruptions show a range in temperature and the thermal variability is consistent with the geochemical variability. Whole rock data have been used to compare the Rotoaira eruptive sequence to other eruptions from Tongariro as well as eruptions from Ruapehu. The data show that the Rotoaira sequence is more Mg- and Fe-rich than younger Tongariro eruptions. Correlation between distal, medial and proximal deposits has been attempted using glass geochemistry to fingerprint the deposits in order to determine the vent location. The data suggest that North Crater is the source of at least one episode of the Rotoaira eruptive sequence, located on the northern side of Tongariro massif. North Crater is also suspected to be the source vent for other two eruptions in the Rotoaira sequence. ORAL MORPHING IN AND OUT AND ROUND- ABOUT Michael K. Eagle Geology Department, University of Auckland, Private Bag 92019, Auckland. Natural History Department, Auckland Museum, Private Bag 92018, Auckland. (meagle*auckland.ac.nz) The biodiversity and paleobiogeography of New Zealand and New Caledonian Mesozoic crinoids involve gradual change of species over time, migratory larvae, and an ability to occupy many marine niches. New Zealand Mesozoic crinoid remains are preserved rarely as calcite or ferric morphs, mainly as leached-out external moulds – nearly always as disarticulated elements, mainly columnals. Post-Palaeozoic columnals are generally straight forward to classify within a ‘natural’ taxonomic system to family, genus, and not uncommonly, species level (due to limited morphological diversity), or as “morphospecies”. Triassic crinoids occur in both the Rakaia and Murihiku Terranes of North and South Islands in neritic volcarenite sequences deposited at different times in fore-arc basins within an island arc. Jurassic crinoids are confined to the Murihiku Terrane of both islands, in an accretionary prism of volcaniclastic, metagreywacke sandstones and siltstones (Western Terrane Group) offshore from continental Gondwana. Cretaceous crinoids occur in basement cover rocks in North, South, and Pitt Islands. Early Triassic Nelsonian and Malakovian Holocrinus is the sole survivor of the Permian- Triassic extinction event, recorded only from the Murihiku Terrane. Etalian taxa include Tethyan Dadocrinus, and endemic Maoricrinites; Aoteacrinus occurs in both the Murihiku and Rakaia Terranes. The Middle to Late Triassic sustained a great biodiversity of benthic genera including Tethyan Holocrinus, Tollmannicrinus, Encrinus, Tyrolecrinus, Silesiacrinus, Angulocrinus, Eckicrinus, Singularicrinus, Chelocrinus, the comatulid Paracomatula, and cosmopolitan Seirocrinus and Isocrinus, variously co-occurring in Southland, Catlins, Nelson, and Awakino facies of the Murihiku Terrane. The Triassic-Jurassic second order extinction event was the last to impact greatly upon the evolution of New Zealand crinoid taxa, decimating populations, but appears favourably disposed towards the Isocrinida. Jurassic Tethyan migration is exemplified by benthic Apsidocrinus, Chariocrinus, Hispidocrinus, and dominant cosmopolitan pseudo-pelagic Pentacrinites, andSeirocrinus occurring only in the Murihiku Terrane. These and a new genus are radiated remnants of a depleted biodiversity. Anomalous to the ongoing re-colonisation of New Zealand by larval dispersion is that cosmopolitan sessile millericrinids are almost non-existent. Cretaceous Austral Province benthic Eugenicrinites, Bourgueticrinus, Dunnicrinus, Apiocrinites, Austinocrinus, Balanocrinus, Isselicrinus, Neilsenicrinus, comatulidSemiometra, and pelagic Poecilocrinus demonstrate a continued incursion of Tethyan, and later cosmopolitan faunas. The K/T extinction event had little immediate impact upon genera, with Apiocrinites, Isselicrinus, Neilsenicrinus, and Isocrinus transcending the boundary. A main Tertiary evolutionary thrust involving isocrinids, bourgueticrinids, millericrinids and comatulids radiated from Cretaceous and Palaeocene genera to occupy New Zealand waters today. Extant members of the Crinoidea have remained virtually unchanged in general overall structure and morphology. Extant species are not an ancient remnant, but the consequence of many ‘revival’ episodes over time. ORAL 50 th Kaikoura05 -25- Kaikoura 2005
Page 1 and 2: CHARACTERISATION OF NEW ZEALAND NEP
Page 3 and 4: myrtaceous. One 20 mm diameter flow
Page 5 and 6: ange of lower resolution or fragmen
Page 7 and 8: CRETACEOUS-EOCENE TRANSGRESSION MAR
Page 9 and 10: consists of a well-developed canyon
Page 11 and 12: model. The relative position of the
Page 13 and 14: converts to plate theory. Thus, the
Page 15 and 16: and on the following morning the mi
Page 17 and 18: the LGM grass peak. This period of
Page 19 and 20: offshore west coast to offshore eas
Page 21 and 22: 4 Institut de Recherche pour le Dé
Page 23: VEGETATION AND CLIMATE CHANGE AT TH
Page 27 and 28: few normal faults visible especiall
Page 29 and 30: TRACKING CRUSTAL DIFFERENTIATION AN
Page 31 and 32: EMPIRICAL SCALING RELATIONS FOR SEI
Page 33 and 34: hydrovolcanic eruptions then took p
Page 35 and 36: and that the MTL marks a Late Carbo
Page 37 and 38: faunal changes within these cores w
Page 39 and 40: material at subsurface depths of se
Page 41 and 42: survived through in low numbers in
Page 43 and 44: in the TVZ and southern Havre Troug
Page 45 and 46: Tephra beds are commonly used to ai
Page 47 and 48: The MCC is bounded by deep-seated t
Page 49 and 50: distal alluvial plains where large
Page 51 and 52: Many of the molluscs in the highly
Page 53 and 54: incremental slip history and paleoe
Page 55 and 56: This paper explores what we know of
Page 57 and 58: volcanism and a linear vent oriente
Page 59 and 60: These areas are also described in
Page 61 and 62: 3D IMAGING OF THE FORE- AND BACKTHR
Page 63 and 64: ascending methane fluids/gases of p
Page 65 and 66: THE GRIFFENS ROAD TEPHRAS: VALUABLE
Page 67 and 68: sideritic concretions that occur in
Page 69 and 70: with 63.8%, and then [3] with 49.9%
Page 71 and 72: U-Th-Ra disequilibria data. In part
Page 73 and 74: landslide tsunami in the past. Rece
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core complex mode, temperature driv
Page 77 and 78:
truncating three plutonic suites of
Page 79 and 80:
active, andesitic White Island volc
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and voluminous than at any on Earth
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oundaries and with immature source
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The new era of commercial viability
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TECTONICS OF THE GALATEA BASIN USIN
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performed by the electron backscatt
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25km northeast of the volcano. Alth
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Most of the tectonic blocks in the
Page 95 and 96:
TECTONIC AND NON-TECTONIC CAUSES OF
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The continental shelf of the Povert
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5 Dept. of Mineral Sciences, Smiths
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Adams CJ...........................
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Naish T............................
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